Technical Note 3
Seasoned softwood is a popular choice for house construction in Australia, particularly when used in pergolas, for a number of important reasons: Economical and readily available in lengths of up to 6 m. (For spans over 6 m, check with your supplier) Seasoned to minimise movement of the installed timber Readily available preservative treated against borers and termites. •
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The following table provides an easy comparison of popular seasoned softwood grades and sizes for common timber elements used in residential domestic pergola applications. The sizes of timber are suitable for use with or without a lightweight roof material. Maximum roof mass is 10 kg/m 2 and timber sizes are adequate for wind speeds up to and including N2. Where roof material is placed on the rafter, the rafter must be connected to the verandah beam and ledger and the verandah beam and ledger must be bolted to the post or supporting structure. Refer to Residential Timber Frame Construction Standards, AS1684 for appropriate connectors to be used.
Typical Seasoned Softwood Pergola Layout
Version 1.1 | 26 May 2008 | Timber Development Association | www.timber.net.au
Pergola Rafter Spans for 600 mm and 900 mm Spacing - (Wind Classification N1 & N2) Single Span Continuous Span Rafter Spacing Rafter Spacing Rafter Spacing Rafter Spacing Size 600 mm 900 mm 600 mm 900 mm D×B F5 F7 MGP F5 F7 MGP F5 F7 MGP F5 F7 MGP (mm) 10 10 10 10 90×35 1800 1900 2200 1500 1800 1700 2200 2400 2800 2000 2200 2200 90×45 2100 2200 2700 1900 2100 2300 2700 2900 3300 2300 2500 2700 120×35 3000 3300 3800 2800 3000 3000 3500 4000 3800 2800 3100 3000 120×45 3600 3900 4300 3200 3400 3700 4100 4500 4700 3200 3600 3700 140×35 4000 4300 4500 3300 3700 3500 4200 4700 4500 3300 3700 3500 140×45 4500 4700 5100 3800 4100 4400 4800 5300 5500 3800 4200 4400 190×35 5600 5800 5900 4600 5100 4700 5700 6400 5900 4600 5100 4700 190×45 6000 6200 6800 5200 5600 5800 6500 7200 7200 5200 5900 5800 240×35 7000 7200 7200 5800 6400 5800 7200 7200 7200 5800 6500 5800 240×45 7200 7200 7200 6700 7000 7200 7200 7200 7200 6700 7200 7200 Notes:
1. 2. 3.
Refer to General Notes for information that is relevant for all Span Tables. For design parameters, refer to Figure 7.26, AS1684.2 and 3. Where rafters are equal to or exceed four times their breath, blocking should be used to reduce member distortion.
Size D×B (mm) 120×45 140×45 190×45 240×45 120×45 140×45 190×45 240×45 Notes:
1. 2. 3. 4.
5.
1. 2.
3.
3000 F7
MGP 10
1700 1900 2800 3400
1700* 2000 2700 3300
1700 1900 2800 3400
1700 2000 2800 3300
Refer to General Notes for information that is relevant for all Span Tables. * denotes 600 mm rafter spacing only. Member span is not suitable for rafter spacing greater than 600 mm. For design parameters, refer to Figure 6.22, AS1684.2 and 3. For the pergola beams shown in illustration, the Roof Load Width is the dimension representing half the rafter span plus any rafter overhang. Refer to AS1684.2 and 3 Clause 2.6.4 for other configurations. NS = Not Suitable
Size D×B (mm) 35x70 45x70 35x90 45x90 Notes:
Pergola Beam Spans - (Wind Classification N1 & N2) Roof Load Width (RLW) 1800 2400 F5 F7 MGP F5 F7 MGP F5 10 10 Single Span 1700 2000 2200 1600* 1700 1700 NS 2200 2600 2700 1900 2200 2200 1700* 3100 3500 3500 2700 3000 3000 2400 3900 4500 4300 3400 3800 3700 3000 Continuous Span 1900 2200 2300 1700 1900 1900 1500* 2300 2600 2700 1900 2200 2300 1800 3200 3500 3500 2800 3100 3100 2500 4100 4500 4400 3400 3900 3800 3100
Batten Spans - (Wind Classification N1 & N2) Batten Spacing Batten Spacing Batten Spacing 600 mm 900 mm 1200 mm F5 F7 MGP F5 F7 MGP F5 F7 MGP 10 10 10 650 850 800 500 650 600 NS 650 600 850 1050 1000 650 850 800 650 850 800 1100 1200 1200 850 1050 1200 850 1050 1200 1200 1200 1200 1100 1200 1200 1100 1200 1200
Refer to General Notes for information that is relevant for all Span Tables. Maximum overhang of batten is 250 mm. Refer to AS1684 tables for other overhang spans. NS = Not Suitable
General Notes
1. 2. 3. 4. 5.
All Tables have been reproduced from AS1684 – 2006 Residential Timber Framed Construction Standard and 2 assumes that a roof sheet mass of 10 kg/m is added. Maximum wind speed N2, refer to AS4055 for site wind classification. These tables assume the building practice contained in AS1684 – 2006 Residential Timber Framed Construction Standard and the tables should be read in conjunction with that standard. For design parameters, refer to Figure 4.9, AS1684.2 and 3. NS = Not Suitable
This publication was produced by the Timber and Building Materials Association, in conjunction with the Timber Development Association (NSW). Important notice: The information and advice provided in the publication is intended as a guide only. As successful design and construction depends upon numerous factors outside the scope of this publication, the Timber Development Association (NSW) accepts no responsibility for specifications in, nor work done or omitted to be done in reliance on this information sheet. Whilst all care has been taken to ensure the accuracy of the information contained in this publication, the Timber Development Association (NSW) disclaims, to the full extent permitted by law, all and any liability for any damage or loss, whether direct, indirect, special or consequential, arising directly or indirectly out of use of or reliance on this guide, whether as a result of the Timber Development Association (NSW) negligence or otherwise.
